Filled plastics are used for many products, and various methods for manufacturing such materials into variously shaped articles is well known. One such filled plastic material is simulated marble. Simulated marble products based primarily on filled polymethyl methacrylate are described in U.S. Pat. Nos. Re. 27,093; 3,488,246; 3,642,975; 3,663,493; 3,847,865; and 4,107,135. Some of these patents describe the use of various fillers to provide a variety of advantageous properties to the article, such as translucency, resistance to staining, flame resistance, machineability, resistance to stress cracking, etc.
Simulated marble products of the type indicated may be attractively processed and have become popular for use as industrial and home counter tops. Usually such counter tops have a flat horizontal slab and a smaller vertical backsplash slab which is glued to the horizontal slab to form a square inside corner. Edge pieces are sometimes glued to each of the slabs to improve counter top appearance.
It is recognized by the industry that an integral counter top with a rounded transition between the horizontal and vertical surfaces is particularly attractive and is advantageous for cleaning and, consequently, is often preferred by the consumer. Smaller sink counter top simulated marble products have been molded to form inside corners. The molding process, however, is not economical for larger products, and consequently, counter top products made from simulated marble and having a rounded inside corner are not available for most applications. Recently, a method for bending filled polymethyl methacrylate was developed by the patentee of the present invention. The method and apparatus for bending polymethyl methacrylate is described in detail in Ser. No. 476,506 filed Mar. 18, 1983. The bending process, however, is not available for applications having a molded sink as an integral part of the counter top.
Also, recently, the industry has been shown the use of a molded third member at the corner of horizontal and vertical counter top slabs. The molded third member has flat surfaces to abut the end edges of the horizontal and vertical slabs. The molded third member also has a concave arcuate transition between the flat sides so that when the third member is glued to the horizontal and vertical slabs, the assembly appears to have a rounded transition at the inside corner. The assembly process, however, is time consuming, and it is not uncommon that cracks between the various pieces are quite visible. Additionally, a glue bead at the cracks between the various pieces must be removed by sanding or other process.